This Library, or Virtual Instrument, sounds completely realistic. It actually better than using a real guitar because of editing possibilities and it is much more quiet than using a real guitar.
There are amp and effects built in, but DI is also an option. I use this for a second guitar track and re-amp it when playing live, and nobody has ever suspected that it wasn't a real guitar.
Because of all of the "AI" involved and the incredible detailed scripting built into it, it is very much ready to use right out of the box.
I can not recommend this instrument highly enough.